Young Girl With Light Colored Hair

Bleaching, also referred to as hair lightening or decolorizing, is a chemical process involving the diffusion of natural color pigment or artificial color from hair. Hydrogen peroxide and ammonium hydroxide are frequently used. It has the side effect of raising of the cuticle, making the hair more porous.
If the hair has been coloured, in order to go lighter it must first be cleansed or bleached. However, it is possible to lighten natural (virgin) hair with para dyes and hydrogen peroxide up to 4 levels depending on the product used.